Energy harvesting using an acoustic metamaterial

Acoustic energy is harvested using a piezoelectric-based metamaterial. The considered metamaterial harvester consists of a multi-cell array of acoustic cavities, which are provided with piezoelectric boundaries in a one-dimensional arrangement. Once impacted by an incident parasitic acoustical energy, these boundaries convert this acoustical energy into useful electrical energy. An ANSYS finite element model is developed to model the dynamics of the multi-field energy harvesting, predict the harnessed power, and optimize the performance of the piezoelectric-based metamaterial when coupled with an external load. The predictions of the ANSYS model are validated against the predictions of a lumped-parameter model of the harvester, which is based on the equivalent electrical analog of the harvester. Excellent agreement is observed between the predictions of ANSYS and the lumped-parameter models. The predictions of the models are validated experimentally using a prototype of the harvester consisting of five cells each of which is manufactured from acrylic cylinders provided with piezoelectric bimorphs This arrangement enables harnessing the energy by the two sides of the bimorph in order to maximize the extracted power of the harvester. The frequency characteristics of the output power of the harvester are determined in relation to the bandgap characteristics of the periodically structured metamaterial. The presented work lays down the foundation for two and three-dimensional metamaterial energy harvesters.